1. Field of the Invention
This invention relates to a process for production of hydrogen from water by electrolysis. More particularly, this invention relates to depolarizing the anode of a water electrolysis cell by oxidizing a biomass product which may be monosaccharides, lignins, and mixtures thereof, thereby avoiding molecular oxygen evolution. The process of this invention produces high purity hydrogen electrolytically at cell potentials substantially less than required for normal water electrolysis involving oxygen evolution. The utilization of biomass product provides a cost effective material to depolarize the anode in water electrolysis process. High consumption of biomass product has been achieved with an anode of lead-rich ruthenium pyrochlore compounds.
2. Description of the Prior Art
The use of organic materials to reduce hydrogen overvoltage in electrolysis of brine by addition of a hydroxy carboxylic acid and a phosphorus containing organic compound to the catholyte is taught by U.S. Pat. No. 3,954,581. The organic material added to the brine is not involved in any electrochemical reaction. U.S. Pat. No. 4,175,013 teaches a method of production of oxygen and hydrogen from water in which formaldehyde is electrolyzed cathodically to hydrocarbons of low molecular weight such as methane and ethane, and water being anodically oxidized to oxygen. U.S. Pat. No. 4,160,816 teaches a high hydrogen overvoltage to increase production of formic acid and reduce hydrogen production at the cathode. U.S. Pat. No. 4,089,761 teaches a sewage treatment process wherein oxygen for supply to aerobic or microorganisms is produced at the anode of an electrolytic cell meaintained in the biodigestion compartment of the sewage treatment cell with the cathode being isolated so as to vent hydrogen out of the cell.
The electrolytic oxidation of dextrose in the manufacture of calcium gluconate is known as described in the article "Manufacture of Calcium Gluconate by Electrolytic Oxidation of Dextrose" by H. S. Isbell, Harriet L. Frush and F. J. Bates, Industrial and Engineering Chemistry, Vol. XXIV, No. 4, April 1932, pps. 375-378, wherein it is taught that CaBr.sub.2 is necessary as a catalyst. The article "Electrolytic Preparation of Calcium Gluconate and Other Salts of Aldonic Acids" by Colin G. Fink and Donald B. Summers, Transactions of the Electrochemical Society, 74, 625 (1938), teaches that alkali ferricyanide may be used as a substitute for the alkali bromide as a catalyst in the electrolytic preparation of calcium gluconate. The commercial processes for oxidation of sugars to acids are indirect oxidations, that is, the electrochemical reaction is reduction of bromine followed by a subsequent chemical oxidation reaction.
The Applicant is not aware of prior art wherein a direct electrochemical oxidation reaction oxidizing organic material in the electrolyte is used for depolarization of the anode of a water electrolysis cell thereby avoiding molecular oxygen evolution and reducing the electrolysis power requirements for the production of hydrogen. Nor is the applicant aware of any teachings of the high consumption of biomass product with use of lead-rich ruthenium pyrochlore compounds for the anode of such water electrolysis cells.